CNS 1 Flashcards
Cerebral cortex
- Sensory perception
- Motor control
- Language
- Cognitive functions (thinking, memory, willed action, self-awareness: the mind (?))
Basal ganglia
- Movement initiation
2. Inhibition of muscles antagonist to the desired movement
Thalamus
Sensory “switchboard” which selects and relays sensory signals to cortex
Hypothalamus
- Homeostasis: temperature control, water balance, hunger
2. Emotions: fight/fright/flight
Cerebellum
- Motor timing, scaling, coordination & learning
- Balance and gait
- Eye movements
Brainstem
- Cardiovascular, respiratory, digestive control
- Sleep/wake cycle, arousal
- Balance and posture
- Locomotor initiating centre
Spinal cord
- Locomotor pattern generator
Functions of the Limbic System
- Learning
- Emotion
- Appetite (visceral function)
- Sex
- Endocrine integration
Meninges:
– Three membranes covering the brain and spinal cord
Three membranes
covering the brain and spinal cord:
- Dura mater → tough outer layer
- Arachnoid → spidery intermediary mesh
- Pia mater → delicate inner layer
Meningitis
infection of the meninges
Cerebrospinal fluid (CSF):
- Produced in brain ventricles
- Reabsorbed into venous blood
- Maintains electrolyte balance around neurons
- Bathes & supports neural tissue
Hydrocephalus (“water on the brain”)
occurs when reabsorption is blocked, CSF accumulates; treated surgically
with drainage tubes
Glia → supportive cells in CNS
- astrocytes
- Oligodentrocytes
- Ependymal cells
- Microglia
Astrocytes
a. Physically support neurons (“scaffold”) Astrocyte
b. Form blood-brain barrier
c. Repair: form scar tissue (which unfortunately inhibits regeneration of severed axons)
d. Turnover (recycle) neurotransmitter
molecules
e. Maintain electrolyte balance
([Na +], [K+], [Ca2+], pH, etc.)
Oligodendrocytes
Form myelin sheaths that electrically insulate axons
Ependymal cells
Produce cerebrospinal fluid (CSF)
Microglia
Scavengers: ingest bacteria and debris
Brain tumors:
Neutrons cannot divide, so Brian tumours dont develop form neuronal cells
- Gliomas
- Meningiomas
Blood-brain barrier (BBB):
– Capillaries in CNS are less porous than in rest of body
- BBB protects neurons from chemical fluctuations & harmful agents
- Provides oxygen and glucose (Brain does not have glycogen
stores) - Selectively transports molecules needed by brain (eg. Glucose) while excluding harmful ions, hormones, etc. Problem for drug delivery eg. Dopamine in Parkinson’s disease
Somatic division controls
voluntary(Skeletal) muscle, autonomic division controls involuntary organs (Heart, gut, bladder etc.)
Motor commands conveyed from
CNS to muscles & glands by motor efferent axons
Sensory inputs conveyed to
CNS by sensory afferent nerve axons of the peripheral nervous system (PNS)
Somatic nervous system
Voluntary command : CNS Move!
ANS:
Parasympathetic division: involuntary command (rest and digest)
ANS:
Sympathetic division: involuntary command: emergency!
Spinal Cord
• Conveys signals from sensory receptors to brain and from brain to muscles
Spinal cord contains neuronal circuitry which generates
reflexes and simple, rhythmical movements ( eg. Walking)
How many spinal nerves in spinal cord
31 spinal nerves convey signals to and from spinal cord:
- 8 cervical
- 12 thoracic
- 5 lumbar
- 5 sacral
- 1 coccygeal
• Each spinal nerve innervates a specific area of skin (Dermatome) and a specific set of muscles (Myotome)
Central ‘grey matter’ in spinal cord tract is comprised of
motoneurons, interneurons, dendrites and axons
Surrounding ‘white matter’ in spinal cord is comprised of
bundles of axons (Tracts), conveying sensory signals ascending to brain or motor commands descending from brain
When spinal cord is damaged at a given level, sensation from and the motor control of functions
below that level are likely to be abnormal
